1. Field of the Invention
The present invention relates to a device and method for using a liquid sequestering solidification agent provided to and arranged in a container to convert liquid or fluid based streams provided through a manifold system to the container, into a dirt-like, solid waste form which meets waste acceptance criteria (WAC) for burial at radioactive and other burial facilities.
2. Background Information
Radwaste water in the commercial nuclear power industry is frequently evaporated or processed through a reverse osmosis system (RO) to reduce the volume of the waste fluid being generated and handled. During the evaporation/RO process, the radwaste water will typically be concentrated until the water becomes saturated with one or more constituents or substances found in the water. After the radwaste water is concentrated, the concentrated liquids still need to undergo additional processing to make them ready for disposal.
In the past, evaporate/RO concentrates have usually been dried to dry solid for disposal. This drying process normally took place at the actual nuclear power plant, or off-site at a radioactive waste processing facility. The equipment used for drying is often bulky, difficult to shield for radiological dose, and challenging to mobilize and demobilize. Also; the operating, maintenance and upkeep on this equipment has usually been extremely costly. This is due to the fact that the drying process is very energy and radioactive dose intensive; and the liquids utilized are corrosive and fouling to such equipment.
Patent references in the past prior art appear to set forth inventions including:    1. Kath et al., U.S. Pat. No. 6,030,549, showing a process of encapsulating depleted uranium and forming a homogeneous mixture of depleted uranium and molten thermoplastic polymer;    2. McClure et al., U.S. Pat. No. 5,916,122 showing a method of solidifying specified aqueous wastes by exposing them in measured amounts to neutralized, cross-linked poly-acrylate; being limited to landfill leachates, latex water, storm water, aqueous solutions of glues, and adhesives;    3. McMillan, U.S. Pat. No. 5,344,003 a process for reacting and converting municipal solid waste into a polymer filled product. The process includes the steps of reducing particle size of municipal solid waste and physically removing metals. This process, however, addresses municipal waste solidification using isocyanate or polyurethanes;    4. Kate et al, U.S. Pat. No. 5,431,084, showing a process utilized for solidification of antifreeze waste fluids; but utilizing a primary mixture of an iron adsorption agent with the waste fluid, followed by a water-absorbing acrylic polymer;    5. Holland, U.S. Pat. No. 5,462,785, showing a multi-chambered pillow with a polymer material in the chambers to absorb and solidify liquid hydrocarbons.    6. Rieser, U.S. Pat. No. 5,318,730, showing a process for forming a flexible and impermeable coating over hazardous materials with a thixotropic agent;    7. Tamata et al., U.S. Pat. No. 4,622,175, showing a process for solidifying radioactive waste, where an alkali silicate composition and curing agent is added to a container already containing radioactive waste which has been loaded first with no particular process, device or positional arrangement, for solidification;    8. Blankenship et al., U.S. Pat. No. 5,304,707, shows a method for incapulation of compositions having a continuous aqueous phase having steps of adding core-shell polymer particles into the composition, and then neutralizing the polymer particles, by using an organic or inorganic base so as to swell the polymer particles and absorb substantially all of the aqueous phase.    9. Goudy, Jr., U.S. Pat. No. 5,164,123, shows a process involving admixture of a toxic material with a thermoplastic polymer for the purpose of only coating the material;    10. Ledebrink, U.S. Pat. No. 4,702,862, shows another process involving the use of a thermoplastic polymer, such as radioactive polyvinylchloride, to merely encapsulate solid radioactive or toxic waste;    11. Drake et al., U.S. Pat. No. 4,382,026, shows a process for encapsulating radioactive organic liquids, utilizing dispersion in an unsaturated polyester or vinyl ester resin, curable to a solid;    12. Monden et al., U.S. Pat. No. 4,629,587, shows a solidifying disposal device for filling a thin-walled container of an inorganic material with radioactive waste, and the addition of solidifier. This device appears to teach structural elements including: a table, a filling cap above the table, lifting and lowering mechanism for movement between the table and filling cap until a lower peripheral edge of the filling cap is contacted by an upper peripheral edge of the container utilized; a supply mechanism, substantially different for that used in the present invention, for providing radioactive waste and a solidifier in a specified step process to the filling cap in a specified positional relationship, and a capping member for positional installation on the device's container.    13. Altmayer, U.S. Application 2004/0144682, shows a waste material solidification pouch, where a pre-measured liquid soluble pouch is combined with a pre-measured volume of absorbent crystalline form polymer like sodium or potassium polyacrylate, sealed and contained within the pouch. This is said to allow a known volume of liquid waste material to be solidified by the inclusion of a known number of these pouches into the waste; without the user having to directly place the bulk absorbent solidifying agent into such waste.    14. Tanhehco, U.S. Application 2002/0185156, shows a solidifier device and method of solidification which is designed to utilize two absorbents, each having a different density relative to the waste to be solidified. There appears to be no means of delivering waste to an already existing container housing a uniform polymer absorbent, and no manifold means for delivering waste fluid to different positions within the container; nor for doing this at a preselected ideal pressure and flow rate.    15. Holland, U.S. Pat. No. 5,462,785, shows a liquid hydrocarbon sorbing and solidifying pillow. The absorbed waste material is solidified within the pillow into a rubber-like mass. The device is provided with a number of layered, internal textile-formed chambers secured by quilted seams which divide the pillow into two columns of stratified pockets; with absorbing polymer inside each chamber. This reference indicates that it seam also creates consolidation points acting as flow channels for migration or entry of a spill or leak.
All of the prior art references found indicate distinctions in relation to the present invention. None of the references teach show or provide for: merging and bonding of solidification agent and waste fluid into a safe solidification product have a dirt-like consistency; where the waste is conveyed into a container already having a preselected level of a solidification agent by means of a manifold system.
In this regard the prior art does not show the introduction of waste material through a manifold system in the container which is stationary or pivotable or positionable within the container; i.e., from position-to-position or level-to-level within the container or receiving unit, already containing a preselected level or volume of absorbing polymer within a non-chambered container.
Additionally, none of the prior art references provide for control of waste fluid flow rate and pressure at the openings (apertures) of a manifold subassembly or system, as shown in the present invention.
Accordingly, the prior art references show no ability to evenly spread and solidify waste from level to level (layer to layer) of one or more pre-positioned layers or levels of solidification agent (polymer); or the ability to work with changing levels of absorbing polymer as waste fluid enters the container proximate to such polymer levels.
Additionally, part of the many disadvantages of the prior art methods and devices include the fact that handling and transporting radioactive solids after conventional evaporation and drying can be extremely complicated and costly. En this regard, since the drying processes increases the concentration of radioactive materials, it often requires that the shipment of radioactive material to a burial site; utilize highly specialized, shielded casks to protect the general public, under Federal regulation guidelines, from radiation exposure.
Also, the resulting higher radioactive waste classification, in this regard, further limits the potential burial sites available to, essentially, one such site in the country, at the time of filing for this Patent. Further complications exist because of the potential in the future of an available burial site, to place further volume and waste classification limits on many of the commercial nuclear plants and radwaste generators transporting radioactive material. If this does become the case, plants and sites disseminating radioactive materials might we be required to store radioactive waste material on or near their own location.
However, the greatest dilemma, involving the conventional drying process, involves the cost, itself. The cost of performing final evaporation and drying of large quantities of concentrate is extremely expensive. This is especially true, when one considers all of the operating and maintenance costs associated with such a process. Both the high salt concentrations and organic constituents hamper efficiency rates and pose difficulties in material-handling. Therefore, corrosion and fouling from the salts and organics, constituting a part of the conventional process, drive up maintenance or upkeep costs.
Another important concern in the conventional process is the exposure of personnel to radioactivity. In this regard, just as the concentration of the salts and constituents increases during the evaporation and drying process, so does the concentration of the radioactive species. This leads to higher radioactive activities; which, in turn, results in higher exposures of radioactive dose to personnel in the area of use.
Another major complication of the evaporation/drying process is that the evaporate/RO concentrates can become contaminated with organic constituents which prevent the drying of concentrates to a condition and solid state required by burial sites for disposal. In this case, special remediation techniques are required. These remedies increase disposal costs and subject personnel to exposure of radiation.
The option of repackaging radioactive material as shown in the prior art, in suitable burial containers also entails similar problems.
Also; water, semi-fluid or other similar waste forms produced under prior art devices and methods, frequently require double containment when being shipped to a waste processing facility. This poses very high risk for waste generators. Transportation accidents have also occurred during such shipments. This has generated great public concern. It has also led to very high costs when it has been necessary to correct the effects and dangers of such accidents.
Therefore, a more simple process and device to carry out such a process providing for lower operation cost, simplicity of maintenance and better protection from radiation exposure; would be highly advantageous to the nuclear industry.
Also, the evaporate concentrates and/or reverse osmosis (RO) concentrates used in the prior art methods and devices frequently expose personnel to hazardous radioactive dose rates; and require that substantial radiation protective means be in place to limit such exposure. Therefore, any process, or device for carrying out such a process, which minimized exposure through time, distance and shielding would substantially increase worker safety and benefit the entire industry.
It is, therefore, an object of the present invention to provide a device and process which utilizes liquid sequestering agents; i.e., a solidification agent, polymer, or media; to convert liquid based streams or more solid fluids into a dirt-like, solid waste form which meets waste acceptance criteria (WAC) for burial at all radioactive burial facilities.
It is also an object of the present invention to provide a device and method for using a liquid sequestering solidification agent provided to and arranged in a container to convert liquid or fluid based streams provided through a manifold system to the container, into a dirt-like, solid waste form which meets waste acceptance criteria (WAC) for burial at radioactive and other burial facilities.
It is also in object in this regard to provide a device and associated method where a solidification agent such as a polymer is added to and/or arranged within a container where admixtures can be added for solidification, and a fluid waste or waste stream is provided to or introduced within the container at a preselected level within the container by a manifold system or subassembly having specially designed holes, for production of a dirt-like solid within the container.
In this same regard, it is a further object of the present invention, as an additional embodiment thereof, to utilize the contour, configuration or shape within the container for advantageous mixture of solidifying agent and fluid waste stream at the desired level within such a container.
It is another object to provide a solidification process and device for carrying out this process, through its related included embodiments and aspects, which simplifies prior art processes, increases efficiency and improves radiation protection.
In this regard, advantages over the prior art include, without limitation, the following aspects:
The device and process of the present invention does not utilize heat. Therefore, direct energy costs are eliminated. Also, support utilities such as service air, service water, and so forth, are minimal. Indirect utility costs are, therefore, essentially, also eliminated.
Most of the equipment and materials utilized in the solidification device and process of the present invention are disposable or low cost items. This reduces or minimizes maintenance costs. Therefore, the required initial capital investment or costs are minimal.
In a related aspect, the process and device of the invention utilize technology which minimizes maintenance down-time and costs. It also enables it to run relatively trouble-free. This limits the time spent in physical contact with the device and process; and reduces exposure of work-personnel to radiation.
The mixing of waste and solidification media in the present invention can be mediated through remote mechanical and/or computer assisted controls. Such controls can facilitate original or initial placement of one or more manifold subassemblies, and can, during the process, reposition one or more of such manifold units. This further limits contact and exposure of personnel.
While dose rates for concentrates being processed varies from 1 to 1,000 mRem, the compact nature of the device of the invention allow it to be shielded more efficiently. This also facilitates lower personnel-exposures.
Drying complications are avoided. This precludes the presence of materials or mixtures in a semi-fluid (or peanut-butter-like) consistency, which would render such materials unsuitable for burial and require additional costs to remedy.
The waste form resulting from use of the device and process of the present invention is more likely to remain in one of the lower waste classifications. This improves the ease and efficiency of transportation and disposal. Also, retaining such material in a lower waste classification provides more options as to disposal in terms of available disposal or burial sites.
These options and others of the invention manifest the capability of producing a dirt-like product in situ, or on the site of burial. The resulting dirt-like product from the device and process of the invention can be mixed with other waste materials in large open trenches, or other convenient places. This will minimize the burial costs by maximizing the burial options and degree of efficiency involved. Additionally, the dirt-like product of the present invention will be readily transferable or flowable in nature. This will provide additional options in its use as a filler material in waste containers. Such options will better utilize burial volume, and decrease burial costs.
Therefore the waste product resulting from the device and process of the invention will be subject to easier shipment. Less expensive shipping containers will be needed. Also, because of the nature of the invention's waste product, such shipping containers would be recyclable.
Importantly, though various types of water solidification processes, and associated devices, in the prior art appear to have used similar polymer media; such structures and processes have utilized only rudimentary mixing methods. These mixing methods have included, among others, simply dumping solidification media into a waste liquid or throwing pillows or packets into a waste spill or container. Other crude mixing techniques have been used, such as the employment of a shovel or paddle to attempt to provide for distribution of the media into the waste material being treated.
Additionally, the prior art devices and processes involve use under exposed conditions. This exposes work personnel to radiation dangers because of the inherent human contact involved in such operations. Therefore, in these situations, such mixing can only be done with liquids having low gamma activity. In such mixing environments, efficient media utilization does not occur because of poor waste distribution and loading. Therefore, the ability to meet the burial waste acceptance criteria is unreliable, unless the waste container is heavily dosed (over-dosed) with solidification agent. The present invention, therefore, solves a significant problem in this regard, in the prior art. Also, as discussed in part above, the solidification of evaporator and RO concentrates in these processes; present a great challenge to work with in that they have much higher ionic concentrations. The reactivity of the solidification agent is slowed down and requires higher amounts of media to bring about the same degree of solidification. Also, as discussed, due to the elevated radiation dose rates that are normally associated with evaporator and RO concentrates, direct contact by personnel necessitated by crude mixing techniques cannot be reasonably accomplished.
Evaporate concentrates also have the unique problem in the prior art of generating higher temperatures, often in the range of bout 150 degrees to 210 degrees Fahrenheit. This causes very rapid solidification. Such chemical and physical states require very rapid and consistently even distribution of the media. The present invention resolves all of these problems in the art.
Therefore, the teachings of the present invention in terms of its solidification process, and related structure for carrying this out, were developed to overcome the problematic issues in the prior art of ionizing radiation exposure, process temperature effects, reaction rates, volume reduction efficiencies, the ability to evenly distribute and solidify waste fluid and solidification agent, direct/indirect costs (operational, maintenance, utilities, etc.), operational practicality, and the ability to handle waste/radioactive material. Improvements over the prior art also, therefore, include, among others, the improvement in containment-qualities of the liquid and vapor phases; and related prevention from radioactive contamination in findings, testing and qualifications inherent in such operations. The present invention also offers improvement of remote control applications. This permits safe remote operation and minimizes personnel exposure during solidification and container closure operations.
It will, therefore, be understood by those skilled in these technologies that substantial and distinguishable device, process and functional advantages are realized in the present invention over the prior art. It will also be appreciated that the present invention's efficiency, adaptability of operation, diverse utility, and distinguishable functional applications all serve as important bases for novelty of the present invention.